1. Field of the Invention
The present invention relates to a cemented optical element in which a convex lens and a concave lens are bonded together.
2. Description of Related Art
Conventionally, a cemented optical element is used in an imaging lens or an optical system of an optical pickup device. Generally, in this cemented optical element, a convex lens and a concave lens are bonded together with an adhesive.
For example, JP 2003-139914 A discloses a cemented optical element in which a spacer for regulating the thickness of an adhesive layer is disposed between a convex lens and a concave lens. In this cemented optical element, the cylindrical end surface of the convex lens is used to fix the spacer.
Recently, further reduction in the thickness of an apparatus (for example, a digital camera), in which a cemented optical element is mounted, has been required. Because of this requirement, a reduction in the thickness of a cemented optical element also has been required.
However, in the case where the length of the end surface of the convex lens is long enough to fix the spacer, as in the cemented optical element disclosed in JP 2003-139914 A, there is a limit to reducing the thickness of the cemented optical element.